The stimulatory effect of testosterone propionate and 17 beta-estradiol on 5'-methylthioadenosine phosphorylase activity in rat target tissues.

The effect of castration and subsequent administration of 17 beta-estradiol and testosterone propionate on 5'-methylthioadenosine phosphorylase activity in rat target tissues was studied. Castration 34 days earlier resulted in a 95% reduction in ventral prostate 5'-methylthioadenosine phosphorylase activity and 16 days earlier in a 67% reduction in uterine 5'-methylthioadenosine phorphorylase activity. Four days of testosterone propionate administration stimulated ventral prostate 5'-methylthioadenosine phosphorylase activity 32% above castrate levels, which represented more than 50% of the intact control levels. 17 beta-Estradiol on the other hand stimulated uterine 5'-methylthioadenosine phosphorylase activity 35% above castrate controls within 24 h and with 3 days of continuous hormone treatment to within 97% of the intact control levels. However, castration and subsequent 17 beta-estradiol administration did not affect 5'-methylthioadenosine phosphorylase activity in rat liver and lung. Both prostate and uterine 5'-methylthioadenosine phosphorylase were shown to metabolize 5'-methylthioadenosine to 5-methylthioribose through a 5'-methylthioribose 1-phosphate intermediate. The data suggest aht 5'-methylthioadenosine is not allowed to accumulate in rat target tissues even under conditions which are known to stimulate polyamine synthesis.